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Results for “SIZE PERCEPTION”

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At least 397 records · Page 22Linked to original sources
PubMed1999

Perceptual independence of size and weight by dynamic touch.

Historically, the existence of a size-weight illusion has led to the conclusion that perceptions of size and weight are not independent. A dependence of perceived heaviness on physical volume (perceptual separability), however, is different from a dependence on perceived volume (perceptual independence). Three experiments were conducted to evaluate perceptual independence. The relations between perceived size and weight and physical size and mass were evaluated in Experiment 1. Perceived weight, length, and width were structured only by the corresponding physical variables, whereas variations in volume were not separable from variations in mass. F. G. Ashby and J. T. Townsend's (1986) test for perceptual independence was applied in Experiment 2. Perceived weight was independent of perceived length and volume. Experiment 3 used a magnitude estimation paradigm to investigate the extent to which information-perception relations could be related to the observed patterns of separability and independence.

Adult↗
PubMed2006

Pupillary contagion: central mechanisms engaged in sadness processing.

Empathic responses underlie our ability to share emotions and sensations with others. We investigated whether observed pupil size modulates our perception of other's emotional expressions and examined the central mechanisms modulated by incidental perception of pupil size in emotional facial expressions. We show that diminishing pupil size enhances ratings of emotional intensity and valence for sad, but not happy, angry or neutral facial expressions. This effect was associated with modulation of neural activity within cortical and subcortical regions implicated in social cognition. In an identical context, we show that the observed pupil size was mirrored by the observers' own pupil size. This empathetic contagion engaged the brainstem pupillary control nuclei (Edinger-Westphal) in proportion to individual subject's sensitivity to this effect. These findings provide evidence that perception-action mechanisms extend to non-volitional operations of the autonomic nervous system.

Adult↗
PubMed1965

SOLUTION OF THE INTERMEDIATE SIZE PROBLEM BY PIGEONS.

Pigeons learned to respond to the middle-sized member (S(D)) of a set of three simultaneously presented stimuli with responses to the S(D) reinforced on a VI 1 schedule. They were then tested for several days with other sets of three stimuli. One procedure presented reinforcements on a VI 1 schedule during the test independent of the stimulus chosen when a reinforcement was programmed. The tests were also given under extinction conditions. With the testing carried out with extinction, preference consistently was for the test stimulus most similar in physical size to the S(D). However, when the tests were with reinforcement, random responding resulted. Another effect of testing with reinforcement was an increase in incorrect responding with the training set. Such a test procedure was unsatisfactory for determining the effective aspect of the S(D). The conclusion, based on the data of the extinction series, was that pigeons learned the intermediate size problem on the basis of the discrimination of absolute stimulus properties.

Animals↗
PubMed1992

Optical magnification as event information.

The geometrical optics of approach events is delineated. It is shown that optical magnification provides information about distance and time until collision. An experiment is described in which two objects--white styropor spheres 10 cm in diameter, seen against a white plaster wall--were moved simultaneously at equal, constant speed along straight, converging paths at eye level towards a human observer and towards a common, virtual point of collision which either coincided with the observer's station point or was placed in front of, or behind, that point. Approach events differed with regard to trajectories, distances, velocities, and times-to-collision involved. Events were observed monocularly fixating and binocularly non-fixating, without head movements. The objects always stopped before colliding, and subjects had to respond to the virtual collisions. Most responses were too early, especially for impending collisions at, or behind the observers' station point. Responses for impending collisions in front of the observers tended to be too late, especially for larger total amounts of optical magnification and higher velocities, which together imply shorter times-to-collision. Relative errors were comparatively larger for very short and very long times-to-collision throughout, where events of the first kind were overshot, the latter ones undershot. Results are interpreted with reference to biological theories and the constraints imposed by geometrical optics. Special attention is focused on the issue of unavoidable, necessary confounding of variables in time-to-collision studies.

Acceleration↗
PubMed1984

Area-matching strategies used by young children.

Across three studies, conditions were varied under which children aged 4-5 years matched the area of a rectangle with a given width (or height) to that of a square. In the first study, subjects observed the rectangle being changed in height from trial to trial and had access to their immediately preceding response. Under these conditions, rectangle width (the dimension under subject control) was a linear decreasing function of rectangle height. This function was interpreted as evidence for a hypothetical addition/subtraction strategy for maintaining equality in area between the comparison rectangle and the standard square. As a test of this hypothesis, in a second experiment the subjects were denied access to their immediately previous response, and in a third study they were also unable to observe the rectangle as it was altered by the experimenter between trials. The purpose of these changes was to remove the information necessary for readily implementing an addition/subtraction strategy. In both studies, area matches seemed to be based on a side-matching strategy, such that subjects matched one dimension of the rectangle to one side of the standard square. It was suggested that young children use different cues or strategies with different variants of the matching task because they do not possess a fixed, specific concept of area.

Attention↗